The present invention relates to drive mechanisms for conveyor belt systems and, more particularly, to a free wheel assist drive mechanism for reducing the tension on the conveyor belt used in a spiral conveyor belt system.
Spiral conveyor belt systems are well-known in the art. They are commonly used in applications where it is desired to keep an item moving for an extended period of time within a contained environment, e.g., a product traveling through a refrigeration zone for cooling. As will be recognized by those skilled in the art, a spiral system typically consists of an endless conveyor belt traveling through concentric stacked helical paths whereby an item travels upward in elevation along the helical paths and/or downward in elevation along the helical paths.
Spiral systems typically utilize a cage (sometimes known as a “drum”) for driving the conveyor belt. More particularly, the cage is centrally positioned within the helical path, and may include a plurality of circumferentially-spaced vertical driving bars which contact the inner edge of the belt to impart a driving force thereto. As the cage rotates, the conveyor belt is pulled along its helical path.
In many applications, the cage extends from and is supported by a centrally-located shaft. In turn, the shaft is rotatably supported upon a stationary frame. A drive mechanism is connected to the cage, and rotates the cage with respect to the frame. As the drive mechanism turns the cage, the cage contacts/drives the belt through the helical pathway of the conveyor belt system. Smaller cages often times utilize a center drive mechanism which directly communicates with the center shaft, resulting in rotation of the cage. Larger cages typically utilize a chain and tooth arrangement whereby the chain extends around the circumference of the cage and engages teeth located on the circumference of such cage. The chain in turn communicates with a drive motor.
On spiral conveyor systems, the belt runs continuously from a discharge region of the cage to an infeed region to repeat the spiral conveying. The path between the discharge region and the infeed region of the cage is called “the return path.” In the return path, the conveyor belt runs in the opposite direction to the belt supported on the spiral path of the cage. Moreover, in all cases when the infeed is not aligned with the discharge, the belt must be traversed along a curved return path.
Accordingly, there is a need in the art to guide the conveyor belt along the curved return path back to the infeed of the spiral cage. It would also be desirable to reduce the tension in the belt in the return path.